粗状假丝酵母产酶能力及发酵条件的优化

对一株产脂肪酶粗状假丝酵母(ACCC20231)产酶特性进行了研究.结果表明,在培养基初始pH值6.0、30℃下培养31 h该菌出现最高酶活.对其发酵培养基成分进行优化,确定最适培养基组成为麦芽粉2%,蛋白胨1%,(NH4)2SO4 0.1%,MgSO4 0.5%,以1%棉子油作为诱导剂,优化后该菌株产酶能力明显提高,达6.2 U·mL-1.     

枯草芽孢杆菌脂肪酶基因lipaseA突变文库构建及其生物柴油转酯研究

采用易错PCR方法对枯草芽孢杆菌脂肪酶基因lipaseA进行定向进化,并首次采用对硝基苯棕榈酸酯（pNPP）法进行96孔板高通量筛选。结果表明：第一轮易错PCR没有产生随机突变,第二轮易错PCR反应在Mn2+浓度为0.2 mmol·L-1时,产生了突变菌株。对该条件下构建的文库中124株突变菌株进行pNPP高通量筛选,突变株4B2的吸光度值A405为1.395,与未突变株PET32a lipaseA（A405=0.448）差异显著。测序结果表明,突变株4B2脂肪酶基因lipaseA有5个核苷酸位点发生了突变,其中3个是同义突变,2个是错义突变,分别是82位的天冬酰胺（AAU）突变为酪氨酸（UAU）,143位的赖氨酸（AAG）突变为苏氨酸（ACG）。突变株4B2发酵上清液转化生物柴油的转酯效率较对照菌PET 32a lipaseA有明显提高,前者为79.5%,后者为49.72%。本研究为枯草芽孢杆菌脂肪酶lipaseA转酯活性位点的探索奠定了基础。     

新型纳米凝胶包被生物炭基固定化酶研究

[目的]探讨一种新型的脂肪酶固定化载体。[方法]采用酶底物类似物油酸分子修饰的纳米凝胶包被生物炭表面,首次制备出一种新型高效的纳米凝胶包被生物炭基质作为脂肪酶酶固定化载体。[结果]通过油/水界面的活化效应激活脂肪酶分子的催化活性位点,并通过凝胶的溶胀/退溶胀作用增强脂肪酶的固定化效果,所制备的新型固定化脂肪酶的催化活性和催化稳定性都得到了充分提高。[结论]新型固定化脂肪酶为酶固定化技术研究提供了材料。     

气调密闭贮藏对芝麻品质的影响

芝麻营养和药用价值高,应用潜力巨大,但贮藏稳定性差。为找到一种绿色、经济的芝麻贮藏方式,利用充CO_2、充N_2、抽真空、密封等方式分析了不同气调密闭贮藏方式下芝麻的水分、粗蛋白、粗脂肪、过氧化值、酸价、脂肪酶活性、脂肪氧化酶活性、脂肪酸等理化指标的变化,探究了不同气调密闭贮藏方式对芝麻品质的影响规律。结果表明:气调密闭贮藏能有效延缓芝麻的氧化酸败,尤其是充CO_2或充N_2气调密闭贮藏可显著降低芝麻贮藏过程中酸价和过氧化值的增加幅度,减轻脂肪的氧化酸败,基本保持原有品质。     

日粮中添加罗格列酮和梧桐子油对绵羊脂代谢相关酶活性的影响

为研究日粮中添加硬脂酰辅酶A去饱和酶(SCD)的活性促进剂(罗格列酮)和抑制剂(梧桐子油)对绵羊背最长肌及皮下脂肪组织中的脂肪酸合成酶(FAS)、脂蛋白脂酶(LPL)、乙酰辅酶A羧化酶(ACC)以及SCD酶活性的影响,选18只体重为27.71±2.64kg、生理状态相似的杂交公羊(美利奴♂×小尾寒羊♀),将其随机分为3组,每组6只,单栏饲养。对照组饲喂基础日粮,梧桐子油组饲喂基础日粮+15g/d梧桐子油,罗格列酮组(L组)饲喂基础日粮+8mg/d罗格列酮。结果表明:1)与对照组相比,罗格列酮可以显著提高绵羊背最长肌中LPL、SCD和皮下脂肪中FAS酶的活性(P0.05),然而,对背最长肌和皮下脂肪中ACC酶的活性没有影响。2)与对照组相比,梧桐子油抑制了绵羊背最长肌中ACC和SCD酶的活性,但对皮下脂肪中的ACC、FAS、LPL和SCD酶活性没有影响。本试验表明罗格列酮可以通过增强机体对胰岛素的敏感性,进而提高SCD和FAS的活性,另外罗格列酮还可以通过激活PPAR-γ,进而提高组织中LPL的活性;富含不饱和脂肪酸的梧桐子油可以通过抑制ACC的基因表达而影响组织中其酶活性的变化,SCD的活性受到梧桐子油中苹婆酸和其他多不饱和脂肪酸的抑制作用而表现出活性降低的结果。     

高产脂肪酶菌株的筛选鉴定

通过变色圈法和透明圈法从泥土中筛选出脂肪酶产生菌,并根据菌株的菌落形态、革兰氏染色和16SrDNA序列分析确定筛选得到菌株的种属。采用罗丹明B(Rhodamine B)平板初筛出51株脂肪酶产生菌,以荧光圈直径或透明圈直径与菌落直径的比值(HC)为指标,选取HC1.60的9株脂肪酶产生菌,采用橄榄油乳化液平板进行复筛,对HC进行测量比较筛选出1株高产脂肪酶的菌株L-17,其HC为2.27。利用透明圈法对菌株L-17的粗酶液的酶活力进行测定,HC为3.07,表明菌株L-17具有较高的酶活力。菌株L-17经初步鉴定为洋葱伯克霍尔德菌(Burkholderia cepacia),为一株高产脂肪酶的菌株,具有潜在的研究和开发价值。     

Effect of dietary bile acids on growth,body composition,lipid metabolism and microbiota in grass carp (Ctenopharyngodon idella)

To investigate the effects of dietary bile acids (BA) on growth and metabolism of lipid in grass carp (Ctenopharyngodon idella, C. idella) at high dietary lipid level, a basal diet (50 g kg^–1 lipid, 5L group) was supplemented with 20 g kg^–1 soybean oil (70 g kg^–1 lipid, 7L group); then, 0.06 g/kg BA was added in 7L diet to form the third diet (7L+BA group). The 96 C. idella (69.86 ± 6.24 g) were divided into three groups (duplicate per group) and fed three diets, respectively, for 8 weeks, and then, growth and lipid metabolism were determined. Results showed that growth of fish in 7L+BA group was significantly higher than 5L and 7L groups. The lipid level in whole body, hepatopancreas and muscle of grass carp in 7L+BA group were significantly lower than 7L group. Relative expression of lipid catabolism genes in hepatopancreas and muscle of 7L+BA group was significantly higher than 5L group. The amount of microbiota in intestine of fish in 7L+BA group was significantly higher than the other two groups. The present results indicated that BA in 7L diet improved growth of fish by increasing protein synthesizing, decreasing lipid content in fish body and by regulating amount of microbiota in intestine of fish.     

Research and Application of Marine Microbial Enzymes: Status and Prospects

Over billions of years, the ocean has been regarded as the origin of life on Earth. The ocean includes the largest range of habitats, hosting the most life-forms. Competition amongst microorganisms for space and nutrients in the marine environment is a powerful selective force, which has led to evolution. The evolution prompted the marine microorganisms to generate multifarious enzyme systems to adapt to the complicated marine environments. Therefore, marine microbial enzymes can offer novel biocatalysts with extraordinary properties. This review deals with the research and development work investigating the occurrence and bioprocessing of marine microbial enzymes.     

产脂肪酶菌株的筛选及其脂肪酶的双水相分离

从土壤中筛选到了两株产脂肪酶的菌株真菌A和真菌B。测定二者酶活,并对真菌B所产脂肪酶的双水相萃取体系进行了优化。结果表明,真菌A酶活为26.5U/mL,真菌B酶活为15.0U/mL,而真菌A比酶活为6618.62U/g,真菌B比酶活为7332.20U/g,选取真菌B为研究对象。最佳PEG分子量为2000,最佳PEG浓度为200g/L,最佳硫酸铵浓度为250g/L。     

脂蛋白脂酶基因及其多态性研究进展

脂蛋白脂酶主要催化乳糜微粒和极低密度脂蛋白中的甘油三酯水解产生不饱和脂肪酸和单酰甘油,影响脂肪代谢,是动物肉质候选基因。综述了脂蛋白脂酶的生物学功能、基因结构,以及多态性与动物肉质关联的研究进展。